Rotor and rotor bearing assembly

ABSTRACT

A reduction mill is provided with a removably mounted rotor and rotor bearing assembly which may be readily removed from the reduction mill for repairs and servicing. The rotor has attached thereto a plurality of radially extending hammer blades operative during rotation of the rotor to pulverize and reduce in size materials flowing through the reduction mill. The rotor is rotatably mounted by means of a pair of rotor bearings and the rotor and rotor bearings are detachably mounted as an integral unit to a subfloor of the reduction mill.

Miner et ai.

[4 Mar. 2, 1972 [54] ROTOR AND ROTOR BEARING ASSEMBLY [72] Inventors: William W. Miner, Hightstown, N.J.; Ro-

land Owens, Verdon, Nebr.

[73] Assignee: Mil-Pac Systems, Inc., Mountainside, NJ.

[22] Filed: Apr. 9, 1970 [2!] Appl. No.: 27,029

[52] U.S. Cl ..241/185, 241/285 [5 1] int. Cl. ..B02c 13/14, B02c 13/26 [58] Field otSearch ..241/185, 191, 194, 220, 257, 241/275, 277, 285, 286,288,186 R, 188 R, 188 A, 259

[56] References Cited UNITED STATES PATENTS 2,290,379 7/1942 Peterson ..241/186 R 2,543,599 2/1951 Rietz ..24l/i86 R 2,682,374 6/1954 Rietz ..24l/i86 R 3,380,672 4/1968 Weispfenning ..24l/19l X 3,552,663 1/1971 Royals ..241/257 X 3,329,357 7/1967 Miner ..24l/285 Primary Examiner-Robert L. Spruili Attorney-Robert E. Burns and Emmanuel J. Lobato [5 7] ABSTRACT A reduction mill is provided with a removabiy mounted rotor and rotor bearing assembly which may be readily removed from the reduction mill for repairs and servicing. The rotor has attached thereto a plurality of radially extending hammer blades operative during rotation of the rotor to pulverize and reduce in size materials flowing through the reduction mill. The rotor is rotatably mounted by means of a pair of rotor bearings and the rotor and rotor bearings are detachably mounted as an integral unit to a subfloor of the reduction mill.

8 Claims, 2 Drawing Figures PATENT'EuMAm I972 3.652.022

SHEET 2 OF 2 ROTOR AND ROTOR BEARING ASSEMBLY The present invention relates to reduction mills and more particularly to reduction mills of the vertical type having a vertically extending rotor.

Conventional reduction mills employ a rotationally driven rotor having a series of hammer blades attached thereto for pulverizing both wet and dry materials. Frequently, metal, rocks, wood and other relatively hard materials are fed through the reduction mill necessitating a periodic sharpening of the hammer blades as well as their replacement whenever they become broken or otherwise damaged. Another serious problem encountered is that of contamination of the rotor bearing by liquids released during a pulverizing dperation and such liquids interfere with a smooth running of the reduction mill because of their stickiness and gumminess. Grit and other granular matter cause corrosion and a gradual wearing away of the bearings and such precipitates the total breakdown of the rotor bearings necessitating their replacement.

The present invention is aimed at increasing the efficiency of reduction mills and does so by minimizing their shutdown time. This is accomplished by facilitating the removal of the rotor and rotor bearings from the reduction mill housing by detachably mounting them as an integral unit on a subfloor of the reduction mill housing.

The .advantages of such a construction are numerous. When one rotor and bearing assembly must be removed for servicing or repair, another such assembly may be rapidly installed in its place thereby minimizing the shutdown time of the reduction mill. If a standby rotor and bearing assembly is kept at the mill site, it may be quickly substituted for a defective assembly thereby allowing the defective assembly to be shipped to a repair shop at the convenience of the mill operator while maintaining the reduction mill in service. This eliminates the necessity of emergency onsite repairs which are usually quite costly and frequently extremely difficult to obtain access to because of their location.

It is therefore a principal object of the present invention to provide a composite rotor and rotor bearing assembly which may be readily installed and removed within a reduction mill housing.

Another object of the present invention is to provide a suitable mounting means for removably mounting a rotor and rotor bearing assembly within a reduction mill housing.

A further object of the present invention is to provide a rotor and rotor bearing assembly which is effectively sealed from contact with any material or liquids flowing through the reduction mill.

According to the present invention, the reduction mill hous ing is provided with a subfloor beneath the regular housing floor and the rotor assembly and rotor bearings are mounted for removal together as an integral unit on the subfloor. The reduction mill housing has a removable top cover and after its removal, the rotor assembly and rotor bearings may be withdrawn as an integral unit through the open top.

Other features and advantages of the present invention will become apparent from a reading of the following specification and appended claims when read in conjunction with the accompanying drawings.

FIG. 1 is a side elevation view, partially in cross-section, showing a reduction mill embodying the present invention; and

FIG. 2 is a side elevational view of the reduction mill shown in FIG. 1 showing the rotor and rotor bearing assembly partially extending from the reduction mill housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the reduction mill of the present invention comprises a rotor housing within which is rotatably mounted a rotor assembly 12. The rotor housing has a floor or base portion 13 which is welded or otherwise affixed to a cylindrical side wall portion 14. A circular top plate is removably connected to the cylindrical side wall 14 and is provided with an unobstructed inlet opening 15 through which material is introduced into the interior of the housing. The housing is also provided with a conventional access opening 16 which is normally closed by a removable door 17. A material discharge outlet 18 is provided at the bottom of the housing and may lead to a discharge conveyor or any other suitable disposal system.

The rotor assembly 12 comprises a solid rotor shaft 20 removably connected to a hollow shaft 21 by means of a collar 22. The collar 22 and the solid shaft 20 are splined together and a lock nut 22a is threaded onto the solid shaft to prevent relative axial movement therebetween. A plurality of rotor arms 23 are connected to the hollow shafi 21 and are symmetrically arranged with respect to the axis of rotation of the rotor to ensure that the rotor assembly is dynamically balanced during rotation. In the embodiment shown in FIG. 1, four columns of rotor arms are symmetrically arranged at intervals around the hollow shaft 21 and each column is made up of five rotor arms 23. Extending through each column of rotor arms is a hammer blade pin 24 on which are pivotally mounted a series of hammer blades 25. The hammer blades are pivotally mounted on the hammer blade pin in a known manner and are retained in their axial position along the hammer blade pin by means of spacer washers 27. A conventional sweep hammer 28 is also provided at the lowermost portion of each hammer blade pin and functions to sweep the pulverized material towards the discharge outlet 18 as is well known in the art. The particular number and configuration of rotor arms and hammer blades depends solely upon the particular use to which the reduction mill is being employed and is not critical to an understanding of the present invention.

The rotor assembly 12 is mounted for rotation within the rotor housing by means of a pair of rotor bearings 30 and 31 which are affixed to the rotor shaft 20 by means of an interference fit. The upper rotor bearing 30 comprises a pair of ball bearings 32 and 33 each of which has its inner race connected to the shaft 20 and its outer race connected to a tubular support member 34. Between the inner and outer races are disposed a plurality of antifriction members, such as rollers or balls. The tubular supporting member 34 is welded or otherwise connected to a ring 35 which is connected to a flange 36. The lower rotor bearing 31 comprises-a self-aligning thrust bearing which rotatably supports the lower portion of the rotor shaft 20. The rotor bearing 31 is a cartridge ball bearing and is removably retained in a preselected axial position on the rotor shaft 20 by threaded retaining bolts 39. The retaining bolts 39 releasably hold the outer race or cartridge casing of the thrust bearing 31 against the ring 35 and the flange 36.

The dimensions of the hollow shaft 21 are preselected such that its interior surface extends radially away from the exterior surface of the stationary, tubular supporting member 34 a distance sufficient to create a dynamic seal during rotation of the rotor assembly 12. As the hollow shaft 21 rotates relative to the tubular supporting member 34, the air present within the cavity 34 existing between the two relatively moving parts is likewise given a circulatory motion and as its velocity increases, its pressure accordingly decreases. This reduced pressure condition existing within the cavity 34 allows higher pressure atmospheric air from outside the reduction mill to flow upwardly past the lower bearing 31, the upper bearing 30 and then into the cavity 34. Hence, as the rotor rotates, atmospheric air is continuously fed into the cavity 34' to dynamically seal the upper rotor bearing 30 from contact with any of the material flowing through the housing. The distance between the interior surface of the hollow shaft 21 and the exterior surface of the tubular supporting member 34 is approximately 0.06 inches and such a distance, of course, varies depending upon the size of the reduction mill. The dynamic sealing greatly prolongs the life of the upper rotor bearing 30 by preventing any material within the reduction mill housing from coming in contact with the bearing and its associated packing.

The rotor shaft 20 terminates in a spindle portion 38 which is connected to a drive motor by any suitable transmission system. As shown, one type of transmission system particularly advantageous is a pulley and belt drive comprising a multisheave assembly 40 connected to be rotationally driven by a drive motor (not shown) by means of a V-belt drive 41.

The rotor assembly 12 and the rotor bearings 30 and 31 are mounted by a suitable mounting means, now to be described, for removal together as an integral unit from within the reduction mill housing. The housing floor 13 is provided with a circular opening 50 which is sized to receive therein the flange 36. A ring-shaped subfloor 51 is connected to the floor portion 13 and cooperates therewith to removably support the rotor assembly and rotor bearing. A plurality of threaded holes 52 are provided in the flange 36 and a similar number of holes 53 are provided in the subfloor 51. The holes 52 and 53 are positioned such that they are in alignment when the flange 36 is properly seated and orientated on the subfloor 51. Threaded bolts 54 are used in conjunction with lockwashers to secure the flange 36 to the subfloor 51.

By such an arrangement, the rotor assembly 12 and the rotor bearings 30 and 31 comprise a composite assembly which may be readily removed as an integral unit from the reduction mill housing by merely removing the bolts 54.

FIG. 2 shows in more detail how the rotor assembly and rotor bearings may quickly and easily be removed as a unitary structure and how the rotor bearings are disassembled from the rotor assembly. As aforementioned, the only connecting means connecting the rotor assembly 12 and the rotor bearings 30 and 31 to the reduction mill housing are a series of connecting bolts 54 which are readily accessible from the exterior of the mill housing. Once the connecting bolts 54 and the top plate 15 are removed, the rotor and rotor bearings may conveniently be lifted as an integral unit from the housing 10. This facilitates the repairing of damaged parts on either the rotor assembly or the rotor bearings. Of particular importance is the ease with which the rotor bearings themselves may be replaced once the rotor assembly has been removed from the rotor housing. To service the upper bearing 30, the lock nut 22a is removed whereupon the collar 22 may be slid upwardly off the shaft due to their splined connection. Then by removing the retaining bolts 39, the lower bearing 31 and the rotor shaft 20 may be moved axially downwardly, as viewed in FIG. 2, from the tubular supporting member 34 thereby freeing the upper bearing 30. Once the rotor shaft 20 is disassembled from the tubular supporting member 34, the lower bearing 31 may be easily removed.

In operation of the reduction mill, solid and liquid waste material are fed through the material inlet 15 into the interior of the rotor housing 10. The material is impacted by the rotating hammer blades and is progressively ground and pulverized as it falls to the bottom of the housing. The pulverized solids and any liquids present fall to the bottom of the housing and are swept into the discharge opening 18 by the sweep hammers 28.

What I claim and desire to secure by letters patent is:

1. ln a reduction mill: means defining a housing having a floor portion and through which housing solid material to be reduced in size may be fed; a rotatably mounted rotor removably mounted for rotation within said housing; means on said. rotor operative during rotation thereof to reduce in size solid material flowing through said housing; bearing means mounting said rotor for rotational movement; and mounting means accessible from the exterior of said housing removably mounting said rotor and bearing means on said floor portion for removal together as an integral unit from within said housing.

2. In a reduction mill: means defining a housing through which solid material to be reduced in size may be fed; a rotatably mounted rotor removably mounted for rotation within said housing; means on said rotor operative during rotation thereof to reduce in size solid material flowing through said housing; bearing means mounting said rotor for rotational movement comprising at least two rotor bearings positioned m spaced apart relationship along said rotor, each said rotor bearing comprising an inner race connected to said rotor, an outer race, and a plurality of anti-friction members disposed between said inner and outer races; and mounting means mounting said rotor and bearing means for removal together as an integral unit from within said housing comprising means defining an opening in a floor portion of said housing, support means connected to both said outer races and dimensioned to fit within said opening, and retaining means for releasably retaining said support means within said opening.

3. A reduction mill according to claim 2; wherein said retaining means comprises a subfloor connected to said floor portion and extending across a portion of said opening, and connecting means for releasably connecting said support means to said subfloor.

4. A reduction mill according to claim 2; wherein said rotor comprises a rotor shaft connected to said inner races, and a hollow shaft connected to rotate with said rotor shaft and cooperative with said support means during rotation to effect a dynamic seal between one of said rotor bearings and the material flowing through said housing.

5. A reduction mill according to claim 4; wherein said support means includes a tubular member positioned around said rotor shaft and connected to one of said outer races, a flange integral with said tubular member and shaped to fit within said opening, and means on said flange cooperative with said retaining means for releasably retaining said flange within said opening.

6. A reduction mill according to claim 5; wherein said retaining means comprises a subfloor connected to said floor portion and extending across a portion of said opening, and connecting means for releasably connecting said flange to said subfloor.

7. A reduction mill according to claim 4; further including means for releasably connecting said hollow shaft to said rotor shaft.

8. A reduction mill according to claim 2; wherein one of said rotor bearings comprises a cartridgetype thrust bearing, and means including said support means for releasably maintaining said thrust bearing in a preselected axial position on said rotor.

l t i i 

1. In a reduction mill: means defining a housing having a floor portion and through which housing solid material to be reduced in size may be fed; a rotatably mounted rotor removably mounted for rotation within said housing; means on said rotor operative during rotation thereof to reduce in size solid material flowing through said housing; bearing means mounting said rotor for rotational movement; and mounting means accessible from the exterior of said housing removably mounting said rotor and bearing means on said floor portion for removal together as an integral unit from within said housing.
 2. In a reduction mill: means defining a housing through which solid material to be reduced in size may be fed; a rotatably mounted rotor removably mounted for rotation within said housing; means on said rotor operative during rotation thereof to reduce in size solid material flowing through said housing; bearing means mounting said rotor for rotational movement comprising at least two rotor bearings positioned in spaced apart relationship along said rotor, each said rotor bearing comprising an inner race connected to said rotor, an outer race, and a plurality of anti-friction members disposed between said inner and outer races; and mounting means mounting said rotor and bearing means for removal together as an integral unit from within said housing comprising means defining an opening in a floor portion of said housing, support means connected to both said outer races and dimensioned to fit within said opening, and retaining means for releasably retaining said support means within said opening.
 3. A reduction mill according to claim 2; wherein said retaining means comprises a subfloor connected to said floor portion and extending across a portion of said opening, and connecting means for releasably connecting said support means to said subfloor.
 4. A reduction mill according to claim 2; wherein said rotor comprises a rotor shaft connected to said inner races, and a hollow shaft connected to rotate with said rotor shaft and cooperative with said support means during rotation to effect a dynamic seal between one of said rotor bearings and the material flowing through said housing.
 5. A reduction mill according to claim 4; wherein said support means includes a tubular member positioned around said rotor shaft and connected to one of said outer races, a flange integral with said tubular member and shaped to fit within said opening, and means on said flange cooperative with said retaining means for releasably retaining said flange within said opening.
 6. A reduction mill according to claim 5; wherein said retaining means comprises a subfloor connected to said floor portion and extending across a portion of said opening, and connecting means for releasably connecting said flange to said subfloor.
 7. A reduction mill according to claim 4; further including means for releasably connecting said hollow shaft to said rotor shaft.
 8. A reduction mill according to claim 2; wherein one of said rotor bearings comprises a cartridge-type thrust bearing, and means including said support means for releasably maintaining said thrust bearing in a preselected axial position on said rotor. 